Method for manufacturing composite metal articles



Patented Fen-27, 1940 UNITED STATES,

PATENT OFFICE METHOD FOR MANUFACTURINGCOM- POSITE METAL ARTICLES Application June 8, 1939, Serial No. 278,031

11 Claims.

This invention relates in general to composite metal articles and in particular to the manufacture of composite metal articles having a base metal, of one composition and a coating metal of ii another composition, superior in properties and characteristics in the intended service, fusion bonded together throughout into an integral structure.

The present application is a continuation in it) part of my application Serial No. 182,461 flled December 30, 1937, and my application Serial No. 237,658 filed October 29, 1938.

It is one of the principal objects ,of my invention to provide a method for manufacturing composite metal articles made up of base metal and coating metal of different compositions, united throughout by a fusion bond, in which one of the metals is deposited, beneath a protective blanket of flux, in the molten state against a non-horiaontal solid face of the other metal, and a depth of the face metal is fused substantially at the molten surface of the deposited metal as the level of the deposited metal rises so that the deposited metal and the fused face metal lntermingle and upon solidification unite the metals.

7 It is also one of the main objects of the invention to provide a method for manufacturing unita-ry composite metal articles made up of base metal and coating metal of different composiin tions in which, one of the metals is deposited, be-

neath a protective blanket of flux, in the molten state against a solid non-horizontal face of the other metal and the metals united by fusing a depth of the solid face metal and intermingling 35 the metal thus fused with the deposited metal to unite the metals, the operation being so carried on that throughout its duration the whole top surface of the deposited metal is molten and the face metal in the zone of contact with molten top 40 surface of the deposited metal is fused to present a fused surface throughout the extent of the zone to the rising molten metal.

It is a further object of the invention to provide a method for manufacturing unitary com-' 45 posite metal articles made up of base metal and coating metal of different composition, in which, one of the metals is deposited in the molten condition against a solid non-horizontal face of the other metal and the metals united by the dis- 50 charge of electric current, submerged beneath a protective blanket of flux, the whole of the top surface of the deposited metal being maintained molten during the operation and the electric current discharge being effective to fuse the face 55 metal at the zone of contact between the face metal and the deposited metal whereby the rising deposited metal contacts and intermingles with fused face metal under the influence of the electric current discharge to unite the metals throughout their common extent by a fusion bond. 5 It is also an object of the inventionto provide a method for manufacturing unitary composite metal articles made up of base metal and coating metal of different compositions in which, one of the metals is deposited in the molten condition 10 against a solid non-horizontal face of the other metal and the metals united by the discharge of electric current, submerged beneath a protective blanket of flux, from the end of a metal electrode, or electrodes, angularly directed toward the face to fuse face metal at the zone of contact between the face metal and the top surface of the deposited metal, the electrode, or electrodes, being maintained in fixed positional relation with respect to the face metal and the rising level of the deposited metal whereby the rising molten metal constantly contacts and intermingles with fused face metal under the influence of the electric current discharge to unite the metals by a fusion bond.

It is a still further object of the invention to provide a method for manufacturing unitary composite metal articles in which a metal of onecomposition is deposited in the molten condition against a non-horizontal face of a solid body of metal of another composition and the metals united by the discharge of electric current, submerged beneath a protective blanket of flux, from the end of a metal electrode, or electrodes, angularly directed toward the face to fuse face metal at the zone of contact between the face metal and the rising top surface of the deposited metal so as to constantly present a fused surface to the contact of the rising deposited metal, the deposition of the molten metal, the functioning of the elec- 4o trode, or electrodes, and the dissipation of heat being controlled to fuse a substantially uniform depth of the face metal during the operation.

It is also an object of the invention to provide a method for manufacturing composite metal articles of unitary character in which a metal of one composition is deposited in the molten condition against a non-horizontal face of a solid body of metal and the metals united by the discharge of electric current, submerged beneath a protective blanket of flux, which fuses metal of the face at substantially the rising top surface of the molten deposited metal and intermingles the metals to unite them, the method being carried out as a continuous operation in which the de- Feb. 27, 1940. R. K. HOPKINS 2,191,481

METHOD FUR MANUFACTURING COMPOSITE METAL ARTICLES Filed June 8, 1959 INVENTOR\ ROBERT K. HOPKINS ATTORNEY contact between the molten top surface of they mosphere and to provide a heat conserving and heat distributing blanket that will assure the heat supplied thereunder being distributed throughout at a high temperature level. Flux blankets ranging, when molten, from about one to six inches, or more in thickness, depending on the conditions of the operations, have been found satisfactory.

The base metal and the deposited coating metal are united under the influence of the discharge of electric current, beneath the blanket of flux,

so directed and controlled that a controlled depth of the face metal is fused at andin the zone of deposited metal and face metal of the base. Thus, the rising molten deposited metal constantly encounters fused face metal and intermingles therewith to unite the metals by an integral fusion bond. I preferably obtain this result by discharging electric current from the end, or ends, of one or more electrodes submerged beneath the surface of the flux blanket and angularly directed relative to the face of the base metal, the other terminal of the discharge being the metal, face metal or deposited metal or both, in the zone of the meeting line of the face metal and deposited metal. The face metal fusing electrqde,-or electrodes, may be consumable or substantially nonconsumable as when made of carbon, tungsten, etc. I preferably employ consumable face metal fusing electrodes in wire form and made of metal composed of constituents of the desired coating.

To assure fusion of the base metal throughout the zone mentioned, I may employ a plurality of closely spaced face metal fusing electrodes, or I may employ a comparatively small number of metal and the face of the base metal, in'order to maintain their face metal fusing effect substantially constant, not only is their feed controlled to maintain a substantially constant electrical discharge but their position is also controlled to maintain a substantially constant relation between their discharge ends and the rising top surface of the deposited metal.

The depth of penetration, or depth of fusion, of the face metalis effected by the electrical discharge from, and the movement of, the face metal fusing electrodes, the electrical discharge from, and the rate of feed of, the electrode, or elec-- trodes, that supplies the bulk of the deposited metal and the rate of heat dissipation. For any particular operation these factors are best determined by experiment. The rate of heat dissipation is best controlled by cooling the mold or the base metal, or both. To secure a uniform penetration throughout the height of face metal the chosen values of the factors mentioned are maintained substantially constant.

In practicing the novel method, as for instance, in the manufacture of a composite body made up of a carbon steel base coated with a depth of corrosion resistant alloy steel which may be used directly as such or which may serve as the workpiece out of which plates or sheets are and may be as much as six feet or more in height and five feet or morein width. Body III may be of a thickness ranging from one foot or less to several feet. There is really no limit as to the thickness of body I. as far as the novel method is concerned; the limit in thickness is imposed by the apparatus, rolling mills etc., available for working the body into the final product.

Preparatory to the coating operation body I may be placed in or incorporated into a mold, so as to provide a space l2 between face H and the mold sidu of suillcient size to accommodate the required coating metal. The width of space l2, 1. e., the thickness of the coating, maybe, as far as, the limitations imposed by the novel method are concerned, as small or as large as is desired; however, since physical apparatus must be employed in the coating operation and in the subsequent working operation these apparatus impose some limitations. Thus, with the apparatus here disclosed space H is approximately one and one half inches wide but may be as .wide' as desired.

At present, a three sided copper mold I3 is preferred which'is held against body ill in any preferred manner as by being bolted through flanges H to similar flanges welded to body l0, mold l3 may cover all or only a part'of face I I. Thus, when body I0 is an ingot mold l3 need, as shown, extend only to the region of the crop line so that after coating and working a minimum 0f expensive alloy need be scrapped with the cropped metal of body Hi. The bottom of the mold space is closed by metal block I5 which may be welded to body I0. placed beneath the apparatus and. the water spraying coils I 6 placed around body l0 and mold l3. v

The present preferred apparatus for performing the coating operation includes a bridge I! supported upon upright members IS. A truck 19 is mounted for back-and-forth movement on bridge ll. Truck I! may be manually moved or it may be motor driven and the motor drive manually or automatically controlled. Truck 9 carries thereon bridge members 20 upon which is supported a second truck 2|. Truck 2| is arranged for movement back and forth on bridge members 20 and maybe manually or motor When thus arranged body I 0 is tically. Frame 23 is moved up and down bya screw mechanism, not shown operated by reversible motor 24. Frame 23 carries strip reel 25 and wire reels 28 and 21. Strip 28 passes from reel 26 through tube forming mechanism 29 which is'driven by reversible motor 30 to form strip 28 into a hollow electrode 3| and feed it as such through contact head 32. .-Wire 33 passes from reel 26 and is fed by reversible feed motor 24 throughcontact head 32. Wire 35 passes from its reel 21 and is fed through. contacthead 32 by reversible feed motor 36. a

Above tube forming device 29 is carried a plurality of metering devices each supplied from hoppers 81 and 38 with a material in particle form that is required in the desired coating. The apparatus usually includes six hoppers and their associated metering devices although only two are here indicated. The alloy material from each hopper is independently metered. The

various materials come together in funnel 39 and pass through conduit 40 to enter hollow from each other 'foreach of electrodes 3|, 33

and 35. Head 32 also carries pilot electrode 4| which is preferably of copper and is water cooled to prevent its destruction. The contact devices for electrodes 33 and 35 are shaped to direct their respective electrodes angularly toward face H as shown. Each of the contact devices and pilot electrode 4| is connected to an appropriate source of electric current through its one of cables 42. The other side of the electric current source, or sources, is grounded through another of cables 42 connected to body I. Contact head 32 is water cooled by water that enters through pipe'43 and leaves through pipe 43.

Cables 42 lead into casing 43 which houses the current source, or sources, for the electrodes and the control arrangements and current source, or sources for motors 24, 33, 34 and 36. These motors are connected to their controls and current sources through leads 44, 45, 46 and 41 which issue from casing 43.

The arrangements are such that motor 30 drives device 23 to form and feedelectrode 3| at the rate required to maintain a discharge of chosen predetermined characteristics from its end. Likewise motors 34 and 35 will feed their electrodes 33 and 35 as required to maintain discharges of chosen predetermined characteristics from their end. This means that these latter electrodes will have their ends maintained at a predetermined distance from face throughout the operation. The arrangements are also such that motor 24 moves frame 23 and contact head 32 as required to maintain a discharge of chosen predetermined characteristics from the end of pilot electrode 4|. Thus, contact head 32 and, consequently, the ends of electrodes 33 and 35 are maintained at a constant distance from the surface against which electrode 4| discharges. By means of these controls the positional .relation of the ends of electrodes 33 and 35 relative to the face II and the top molten surface of the deposited metal is maintained constant throughout the operation.

Referring again to the coating operation, after base metal l0 and mold l3 have been assembled ceramic members 5| are positioned at each end of space l2. Members 5| effectively prevent electrodes 33 and 35 from coming into contact with mold I3 and thus, prevent its fusion while in addition assure a complete bondof commerce.

of 'Armco iron. The nickel and chromium re-" ing of the whole of the coating without any unbonded overlap and consequent waste of alloy.

To deposit a coating .of corrosion resisting alloy, as for instance the well known |8--8 chrome nickel steel, the strip out of which electrode 3| is formed is chosen of steel or iron of low carbon and low im urlties such as the Armco iron e wire electrodes may also be quired are supplied from hoppers 31 and 38 as nickel shot and ferro-chrome respectively.

For satisfactory results it is advisable to fuse a depth of the metal of body l0 about deep. Thus for example, the feeds and movement of wire electrodes 33 and 35 are adjusted to maintain a discharge at their ends that will fuse, with cooling of the mold I3 and body ID, a A,"

depth of the metal of m n. with cm depth of fusion about 14% of the metal of the coating will be derived from the metal of body II. The chosen adjustment of the feed of electrodes 33 and 35 will also, from experience, show the percentage of metal that these electrodes contribute to the final coatings. The analysis of all of the material being known, the metering of the ferrochrome and nickel and the feed rate of electrode 3| necessary to produce the desired analysis can easily be determined.

, Thus, after all of the metering rates and electrode feed rates are determined and the necessary settings made, contact head 32 is lowered into space l2 and the electrodes fed until they approach block l5; are starters in the form of wads of steel wool or the like are then interposed between the ends of the electrodes and plug IS. The flux blanket 50 is then laid in the mold. The water circulation through contact head 32 and the sprays 15 against mold ,l3 and body I. are then started. After this the various.electrode circuits are closed.

The initial surge of current destroys the arc starters and establishes arcs, between the electrodes and block l5, which are brought to and maintained at the predetermined values by the controls, heretofore mentioned, incorporated in the apparatus. The electric current discharges fuse metal of body |0, electrodes 3|, 33 and 35, block I5 and the metered materials fed through electrode 3| into a common pool which, as it increases in 'volume, rises to progressively cover surface H and to fill space I2. The flux blanket 50 is also fused and brought to a highly heated condition in which condition it not only excludes the atmosphere and fluxes out impurities but also serves to maintain the whole of the top surface metal beneath it in a highly superheated condition so that the union of the metals is facilitated and proper alloying and refining of the deposited metal rapidly takes place.

Electrodes 33 and 35 are angularly directed to discharge in the zone of the meeting line between the surface of the deposited metal 52 and face H of body Ill so as to present a fused surface to the rising deposited metal 52. In order that.

the surface of body Ill be always in the fused condition for the full length of the zone, contact head 32 is oscillated back and forth along the length of space |2 at the proper rate. This rate is best determined by experiment. With the apparatus and body l0 shown, head 32 in oscillating moves through a distance approximately equal to the distance between the discharge ends of electrodes 33 and 35. The oscillation is such that electrodes 33 and 35 closely approach members 5| and thus assure complete bonding of coating 52 to body III for the full width of coating 52 without danger to mold l3. Since in each case the object is to secure an uninterrupted bond throughout between body Ill and coating 52, the number of electrodes, their spacing and the oscillation of head 32 will be chosen to give this result. I

The cooling eflect of sprays It not only aids in maintaining a uniformdepth of fusion into'body are present appear only in the metal I: at and adjacent the very top of thedeposit. Since even this metal solidifies with a body of highly heated fiux above it defects are few indeed.

, After the operation has progressed to the point that the top of flux blanket II approaches a predetermined level, the electric circuits are opened and the deposition stopped. After metal I! has solidified mold I3 is removed. Coated body llisthenreadytobeusedassuchorto beworked as by rolling into plates, sheets and 'thelike.

The invention is not limited to the coating of one or more plane surfaces of a body, such as body I II, but may also be used to coat curved surfaces. Thus, the method of the invention may be used to coat the outside surface of a cylindrical billet I and thus form a composite workpiece out of which coated articles such as bars, wires, structural shapes, tubes, etc. may be made, also, it may be used to coat the inside surface of .an annular body. to form a workpiece out of which inside coated tubes may be made, furthermore, it may be used to coat the outside surface as well as the inside surface of an annular body to provide a workpiece out of which inside and outside coated tubes may be made.

I claim: v Y

l. The method of uniting metals which comprises, depositing molten metal against a nonhorizontal surface of a solid metal body to provide a substantially horizontal molten metal surface that progressively rises and covers said nonhorizontal surface and uniting the metals into an integral'structure by fusing a depth of the solid metal substantially at the surface of the molten metal as the molten metal rises against the solid metal, the fusion of the solid metal being effected by the discharge of electric current through a gap beneath the surface of a blanket of flux, said gap being positioned sufilciently adiacent to the solid metal to fuse said solid metal directly by the heat generated thereat.

2. The method of uniting metals which comprises, providing a mold space defined at least in part by a non-horizontal face of a solid metal body, depositing molten metal into said mold space beneath a protective blanket of fiux to .progressively fill said space and to provide a rising moltenmetal surface that progressively rises to cover said face, maintaining said rising metal surface in the molten condition throughout its extent during themetal deposition, and uniting the metals into an integral structure by fusing a depth of the solid metal at substantially the level of said molten metal surface, the fusion of the solid metal being effected by the discharge of electric current through a gap beneath the surface of the fiux blanket positioned sufliciently adjacent to the solid metal to fuse said solid metal by the heat generated thereby.

3. The method of uniting metals which comprises, providing a mold space defined at least in part by a non-horizontal face of a solid metal body, depositing molten metal into said mold space beneath a protective blanket of fiux to progressively fill said space and to provide a rising molten metal surface that progressively rises.

to cover saidface, maintaining said rising metal surface in the molten condition throughout its extent during the metal deposition, and uniting the metals into an integral structure by fusing a depth of the solid metal body at substantially the level of said molten metal surface by the discharge of electric current through a gap beneath the surface of the-flux blanket and positioned sufficiently adjacent to the solid metal body to fuse metal thereof directly by the heat generated, the electric current discharge being controlled to maintain the full extent of the metal of said body at substantially the level of said molten surface in the fused. condition during the operation whereby a continuous zone of fused metal is constantly presented to contact with said molten surface.

4. The method of coating surface of a solid metal body of one composition with protective metal of a different composition which comprises, providing a mold space defined at leastin part by the surface to be coated, said surface to be coated being substantially vertically disposed, providing a protective blanket of flux in the bottom of said mold space, depositing molten metal beneath said blanketv of fiux to progressively cover said vertical surface, maintaining the full extent of the top surface of the deposited metal in the molten condition during the operation whereby the full thickness of the coating is constantly deposited, uniting the solid body to the deposited metal by the discharge of electric current through a gap beneath the blanket of flux and positioned sufilciently adjacent the solid body to fuse a depth of the solid body directly by the heat and to intermingle the metals, and progressively solidifying prior deposited increments of the molten metal during deposition of subsequent increments. to localize defects in the last portions of the deposited metal to solidify.

5., The method of uniting metals which comprises, depositing molten metal beneath a protective blanket of flux against a substantially vertically disposed surface of a solid metal body metal body of one composition with protective metal of a different composition which comprises, providing a mold space defined at least in part by the surface to be coated, said surface being substantially vertically disposed, providing a protecfive blanket of flux in the bottom of said mold space, depositing molten metal beneath said blanket of flux to progressively cover said vertical surface, and uniting the metals into an integral structure by discharging electric current through a gap, or gaps, beneath the surface of the flux blanket and between the end, or ends, of one or more electrodes and the metal in the zone of intersection of the vertical surface of the solid body and the top molten surface of the deposited metal to fuse a depth of the solid body directly by the heat generated and to intermingle the metal thus fused with the deposited metal, the composition of said electrodes and deposited metal being adjusted to provide a coating of desired analysis.

7. The method of coating surface of a, solid metal body of one composition with protective metal of a different composition which comprises, providing a mold space defined at least in part by the surface to be coated. said surface being substantially vertically disposed, providing a protective blanket of flux in the bottom of said mold space, depositing molten metal beneath said blanket of flux to progressively cover said vertical surface, maintaining the full extent of the top surface of the deposited metal in the'molten condition during the operation, and uniting the metals into an integral structure by discharging electric current through a gap, or gaps, beneath the surface of the flux blanket and between the end, or ends, of one or more electrodes and the metal in the zone of intersection of the vertical surface of the solid body and the molten top surface of the deposited metal to fuse a depth of the solid body directly by the heat generated and to intermingle the metal-thus fused with the deposited metal, the functioning of the electrodes being controlled to fuse a substantially continuous band of the solid metal which band rises with the rising molten surface of the deposited metal whereby the rising deposited metal continuously contacts fused metal of the solid body.

8. The method of coating surface of a solid metal body of one composition with protective metal of a different composition which comprises, providing a mold space defined at least in part by a substantially vertically disposed surface of the solid metal body and in part by ceramic members that close the ends of the mold and extend substantially the full height thereof, providing a blanket of flux in the bottom of said mold, depositing molten metal beneath said flux blanket to progressively cover said vertical surface, uniting the metals into an integral structure by discharging electric current through a gap, or gaps, beneath the surface of the flux blanket and between the end, or ends, of one or more electrodes and the metal-in the zone of intersection of the vertical surface of the solid body and the top molten surface of the deposited metal to fuse a depth of the solid body directly by the heat generated and to intermingle the metal thus fused with the deposited metal, and moving said gap, or gaps, back and forth in said zone of intersection to fuse a continuous band of the solid body, said movement being such that a gap reaches each of the ceramic members whereby a complete fusion bond without unbonded overlap at the edges is obtained throughout the common extent of the solid body and the coating.

9. The method of coating surface of a solid metal body of'one composition with protective metal of a different composition which comprises, providing a mold, said mold having a conductive bottom and being defined at least in part by a substantially vertically disposed surface of the.

solid metal body, providing a blanket of protective flux in the bottom of 'the mold, discharging electric current through a gap beneath the surface of the flux blanket and between the end of a metal electrode and the conductive bottom of the mold to deposit molten metal to progressively cover the vertical surface of the solid body, and uniting the deposited metal with the solid body by discharging electric current through a gap, or gaps, beneath the surface of the flux and between the end, or ends, of one or more surface fusing metal electrodes and the metal in the zone of intersection of the vertical surface of the solid body and the top surface of the deposited metal to fuse a depth of the solid body directly by the heat generated and to intermingle the metal thus fused with the deposited metal, controlling the electric current discharges to maintain the top surface of the deposited metal in the molten condition throughout the operation and to maintain a continuous band of fused metal of the solid body for contact with the rising molten metal, the composition of the electrodes being adjusted to provide a coating of desired analysis.

10. The method of manufacturing composite metal articles that include a base metal of one composition integrally united by a fusion bond to a coating metal of a different composition which comprises, providing a mold having a conductive bottom and defined at least in part by a substantially vertically disposed surface of the solid base metal, providing a blanket of protective flux in the bottom of the mold, discharging electric current through a gap beneath the surface of the flux blanket and between the end of a metal electrode and the conductive bottom of the mold to deposit molten metal to progressively cover the vertical surface of the base metal, uniting the deposited metal with the solid base metal by discharging electric current through a gap, or

'gaps, beneath the surface'of the flux and between the end, or ends, of one or more surface fusing metal electrodes and the metal in the zone of the intersection of the vertical surface of the base metal and the top surface of the deposited metal to fuse a depth of the base metal directly by the heat generated and to intermingle the metal thus fused with the metal deposited from the electrodes, moving the surface fusing electrodes to maintain a continuous band of fused base metal, controlling the dissipation of heat to obtain a progressive upward solidification of the coating metal, and adjusting the composition of the electrodes, their rates of fusion, the rate of movement of the surface fusing electrodes, and the rate of heat dissipation to obtain a substantially uniform depth of fusion of the base metal throughout and a coating of predetermined analysis.

' 11. The method of manufacturing composite metal articles that include a basev metal of one composition integrally united by a fusion bond to a coating metal of a different composition which comprises, disposing a surface of the solid base metal angularly to the horizontal, depositing molten coating metal to progresively cover the angularly disposed surface, and uniting the metals by fusing a depth of the base metal at the angularly disposed surface as the molten metal 2 rises thereagainst, the fusion of the basemetal being effected bythe discharge of electric current through a gap beneath the surface of a blanket of protective flux, said gap being positioned sufficiently adjacent to the base metal to ROBERT K. HOPKINS. 

